Muhammad ibn Ali ibn Mahbub from Muhammad ibn Al-Husayn from Safwan from Ibn Bukayr from Zurarah who said:
I saw Abu Ja’far عليه السلام, peace be upon him, or he said: “I heard Imam عليه السلام, begin the prayer with seven consecutive Takbirs.
Ali Akbar al-Ghaffari
Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 2, p. 310